In a series of articles that assess the potential impact of Mac OS X 10.5 Leopard, we unpick the hype to see what Apple is really promising with when its new operating system is released next year. First up: the promise of 64-bit computing.
Leopard, the next version of the Mac OS, is due to ship sometime in spring 2007. However, the upgrade has been showcased by Steve Jobs at Apple’s Worldwide Developers Conference, and the Apple hype machine is busy analyzing what the new features will do. We’ve looked at a series of changes – starting here, with the operating system’s promise of 64-bit support.
Full 64-bit support got top billing in Steve Jobs' Worldwide Developers Conference keynote -- it was first on the list of Leopard enhancements he previewed, ahead even of Apple's striking Time Machine backup-and-restore technology. Even at a developer conference, however, 64-bit support was an odd choice for the lead-off position, because it's an option even Apple admits doesn't yet make sense for most applications.
How it works
If you're writing an application that requires huge amounts of memory (more than 4GB), or needs random access within data sets larger than 2GB (as opposed to, for example, video-editing applications that read and write very large files but work with only a subset at any one time), it's convenient to deal with 64 bits of data at time. Most of today's Mac (and Windows) applications only use 32-bit chunks of information. Apple has for years offered developers some ways to work with 64-bit data, but those involved working around the fact that the Mac OS and most of the hardware it ran on basically added up to a 32-bit environment.
Things will be different in Leopard: Developers can now build fully-fledged 64-bit Mac applications. However, developers converting existing Mac programs will face a fair bit of work. Not only their own code, but every library, framework, and plug-in their programs use will have to be modified and recompiled.
Even then, there's not always a clear-cut case to move to 64 bits. First, 64-bit code will work only on G5 or Core 2 processors -- developers will still have to deliver 32-bit versions for users with Macs based on G3 and G4 PowerPCs or even with Intel's first-generation Core Duo and Core Solo CPUs. The the current MacBook, MacBook Pro, iMac and Mac mini product lines will lag behind in the 64-bit stakes.
Second, some 64-bit programs will actually perform more slowly than 32-bit equivalents, particularly on G5 Macs. Although most applications are likely to pick up some performance by going 64-bit, the benefits are not likely to be overwhelming, even on the new Mac Pro and future models with Core 2 processors. The main problem is that going from 32- to 64-bits results in inflated code, which means less of it fits in the processor's L1 and L2 caches, and more relatively slow calls to memory are required.
Who's it for, then?
Developers of certain types of programs that work with huge amounts of data -- some scientific computing applications, large database and data-mining systems, large-scale CAD/CAM applications, and specialized image processing programs, to name a few -- will appreciate Leopard's full, native support for 64-bit computing. From a creative point of view, 64-bit computing should allow for your applications to take advantage of more RAM. This should speed things up -- but obviously depends on the software companies optimizing their applications for the 64-bit operating system.
What it means
In a decade or two, 32-bit computing may only be a distant memory, and the Mac OS (or whatever succeeds it) and the hardware it runs on will be fully optimized for 64-bit operation. By then, in hindsight, the addition of 64-bit application support in Leopard will look like a milestone on an important evolutionary path. But in the near term, it's mostly of interest to developers of specialized technical applications. For most Mac fans -- even graphics professionals and other power users -- this is one leap forward that's not likely to produce much of a splash when Leopard is unleashed next spring.